【作者】 陶丽；

【导师】 宋宏伟；

【作者基本信息】 吉林大学 ， 物理电子学， 2014， 博士

【摘要】 能源是现代社会发展与进步的必需品。能源的可持续开发与高效率的利用一直是人们追求的永恒课题。目前达到地面的太阳能是现有的技术手段所能耗用的10000倍左右。因此利用光伏电池高效、低成本地转化太阳能为人类所用仍然是一项艰巨的任务。一个限制太阳能电池转换效率的主要问题在于光伏电池对太阳能全谱的不敏感。在c-Si (Eg=1.1ev)太阳能电池中,由Shockley-Queisser极限定义，最大效率上限为31%。目前，为了增加单节太阳能电池的效率，三价稀土离子由于具有丰富的能级结构能够很好的进行光调控，成为主要的实现有效光谱转换的选择。上转换过程、下转换量子剪裁过程应用到光谱转换层中最为广泛，尽管这些基础研究取得了一定的进展，但在实际应用中仍然存在着不足。围绕着对近红外量子剪裁等基础物理问题的深层次理解，以及亟需深入研究在上转换材料中提高上转换效率、调控上转换发光、在不同基质材料中上转换发光过程的特异性等基础研究内容，我们开展了一系列的研究工作。取得的主要成果有：[1]采用溶剂热的方法制得了LaF3:Sm3+六角相纳米晶材料，系统研究了在可见光激发的下转换近红外发射，得出了在LaF3:Sm3+(0.4mol%)纳米晶中最高的理论量子剪裁效率能够达到193%，考虑到光谱匹配的原因，LaF3:Sm3+纳米晶的近红外量子剪裁在提高Ge基太阳能电池的光谱响应中有潜在的应用。[2]通过系统研究立方相荧光粉NaLuF4: Er3+, Yb3+的下转换量子剪裁过程，总结出了近红外量子剪裁通道，计算了Er3+到Yb3+能量传递效率，并得出荧光粉理论的量子剪裁效率几乎相同(199%),展现了Er3+离子作为激活剂具有高的近红外量子剪裁效率。[3]利用溶胶-凝胶法结合胶晶模板法成功合成了YOF, GdOF和LaOF掺杂Yb3+和Er3+离子的三维有序大孔的上转换反蛋白石光子晶体；研究得出LnOF光子晶体中自发辐射速率的抑制源于有效折射率的变化而非局域态密度的降低；发现LnOF光子晶体的三维有序大孔和薄层状结构降低有效折射率以及抑制局域热效应。此工作对深入理解光子晶体效应作用于稀土离子的上转换发光过程和多功能光电器件的应用有重要意义。[4]我们研究了LnOF: Yb3+, Er3+纳米粉体材料的基质依赖的上转换发射谱，及温度依赖的上转换发射谱，并通过电子自旋共振谱图分析了白光宽带发射的来源。更多还原

【Abstract】 Energy is a necessity of modern social development and progress. Sustainabledevelopment and efficient use of energy has been the pursuit of eternal subject.Currently solar energy reaching the ground is more than10,000times we canconsume by the existing technical means. Therefore, the use of photovoltaic cellsefficiently, cost-effectively converting solar energy for human use is still a dauntingtask. A major problem limiting the conversion efficiency of the solar cell is thephotovoltaic cell is not sensitive to the full spectrum of solar energy. In c-Si (Eg=1.1ev) solar cells, defined by the Shockley-Queisser limit, the maximum efficiencylimit is31%. Currently, in order to increase the efficiency of single solar cellstrivalent rare earth ions have rich level structure which have the capability of goodoptical control, become the main choice for efficient spectrum conversion. Theupconversion process and the process of down-conversion quantum cutting have beenwidely applied to the spectra conversion layer. Although the basic applied researchhas been made some progress, there are still insufficient in practice. Aiming tounderstand the near-infrared quantum cutting deeply and the mechanism ofupconversion process, such as improving the upconversion efficiency, regulating theupconversion luminescence and the specificity of upconversion luminescence indifferent matrix, we carried out a series of research work. The main results are:[1] Pure hexagonal LaF3: Sm3+nanocrystals were prepared via a simplesolvothermal route. The near-infrared down-convesion emissions under visible lightexcitation were systematically investigated. The highest theoretical quantum-cuttingefficiency in LaF3: Sm3+(0.4mol.%) nanocrystals can reach up to193%. Thenear-infrared quantum cutting phenomenon in LaF3: Sm3+nanocrystals have potentialapplications in improving the Ge-based solar cell spectral response, taking spectralmatching to the cause. [2] We studied the cubic phase phosphor NaLuF4: Er3+, Yb3+quantum cuttingprocess under the excitation of visible light. Many strong down-conversion transitionshave been observed and the possible near-infrared quantum cutting channels havebeen summarized in the near-infrared region850-2100nm. The energy transferefficiency has been calculated. Assuming Er3+quantum efficiency of ions is100%,the quantum-cutting efficiency of the phosphor in theory was almost the same199%,which shows the Er3+ion as an activator have a high near-infrared quantum cuttingefficiency so as to improve the spectral response as spectral matching layer and theconversion efficiency of the solar cell.[3] Yb3+and Er3+doped YOF, GdOF and LaOF three-dimensional orderedmacroporous upconversion inverse opal photonic crystals were successfullysynthesized by using sol-gel method combined with colloidal crystal template method.We found that the spontaneous emission rate was inhibited in LnOF photonic crystalscoming from the change of the effective refractive index rather than the lowerlocalized states density. The dimensional ordered macroporous and lamellar structureof LnOF can make the reduction of the effective refractive index of the photoniccrystal and the suppression of local thermal effects.[4] The upconversion luminescence of nanosized LnOF: Yb3+, Er3+powder werestudied.The host-dependent upconversion spectra and temperature-dependentupconversion spectra were studied. In addition, the broadband upconversionluminescence extending visible range were observed in LnOF:Yb3+,Er3+powder samples under high excitation power, and the origin was identified byelectron paramagnetic resonance (EPR). Specific luminescence mechanism iscomplex in the nonlinear optical process (upconversion luminescence process), whichremains to be further studied.更多还原